April Russell

 Hands-on astronomy  Science of modeling  3D printing  Discussion

 Observation  Backyard observing with telescopes  Instrumentation  Mirror grinding  Education/Outreach  Solar system models  Planispheres  Starlab NASA recommends making asteroids out of clay BORING! Where is the technology?

Cheap and easy, but…  Time intensive  Not scientifically accurate  they all start looking the same!  Not exciting!

 Scientifically accurate - see differentiation between asteroids  Variety of materials/printing methods available  Tangible science – show off techniques and get people interested

 Astronomy  Observations/data collection of variation in brightness  Data reduction  Model generation  Inversion (Canopus)  Rectification (MeshLab, other)  Verify with occultations  Additive manufacturing (3-D printing)

Observations Light Curve Occultation Virtual Model Printed Models

 Convert scientific model to printable format  Approximates shape using triangular facets  Add texture (cratering)  Set density / Add void space  May have limits on # of vertices, wall thickness, holes, overhangs, etc  Slices virtual model into digital cross sections  Print Model  Extrusion method builds model in layers; many options

Extrusion/fused deposition (ABS/Plastics) Photopolymerization /Stereolithography (Polymers) Granular materials binding (Polymers/Metals/Food)

Own Machine - $500-$20,000+  Open Source / Kit  RepRap, Makerbot, others  Commercial  Stratasys, 3D Systems, others Services – priced by volume, depends on material  Shapeways, Solid Concepts, others

 Verify your model is printable  Surfaces must be a closed manifold and be assigned the correct normals (in/out)  Not usually an issue for asteroid models  Check maximum size and minimum wall thickness  Optimize your model  Much cheaper if hollow, though printer may require it has a hole  Consider different mediums and colors – think about ceramic, plastics, metal, candy  Consider partial fills, thin shells, and mesh v. solid designs

3D printing offers a new opportunity for hands on astronomy that ties together a variety of exciting fields

 Background Information   elsOf20Asteroids.pdf  Data available at DAMIT website   Images and Video  Occultation%20Geometry.jpg   m   